Each of these ratios is computed over a limited set of E/Q steps (DPPS steps). The energy range of each
ratio is indicated in the name of the ratio. Also, for each ratio, the individual values (numerator and
denominator) that went into the ratio are also available.

There are also GAFs, or group abundance fractions, which are ratios of just the counts. These are designed to capture
measurements with low counts and measurements with higher counts with a statistical consistency.
A group abundance fraction of He++ and H2+ is the ratio of He++ over the sum of He++ and H2+.
Likewise, a GAF of H2+ and He++ is the ratio of H2+ to the sum of H2+ and He++.
Ask Ed Roelof for more details and also see the following: